As early as seventy years ago, golf club designers looked to the benefits of a pendulum-type golf club. Plant U.S. Pat. No. 1,409,966 thus speaks of enabling a golfer to use a "pendulum swing". Plant's club had a club head endwise of a club shaft, with the club head symmetrical about axes parallel to and intersecting the club shaft axis.
The pendulum club pursuit has continued over the years. Hoglund U.S. Pat. No. 3,758,115 shows a club head which has portions extending in x- and y-directions from an identified club center of gravity. A club shaft receiving recess is shown as extending through the center of gravity at a substantial angle of inclination to the z-axis. The shaft is likewise at such inclination angle, being so directed by the angulation of the recess in the club head. Hoglund advises that the resulting stroke is "a natural pendulum type of stroke with no tendency to twist or shock when the ball is struck" (column 3, lines 61-63).
Palmer U.S. Pat. No. 3,037,770 notes that a golfer's arms need move in pendulum-like manner and discloses club structure said to meet such purpose, involving also an angulation of the entire club shaft to the z-axis. A like arrangement is shown in McClure U.S. Pat. No. 1,703,199.
Baumann et al. U.S. Pat. No. 5,253,868 and U.S. Pat. No. 5,257,807 likewise note the benefits of pendulum-type clubs, using the expression "true center of gravity putter" ('807 patent, column 5, lines 59-60). The various club structures disclosed by Baumann et al. in these patents follow the Hoglund patent at least in respect of the angulation of the club head shaft-receiving recess being at a substantial angle of inclination to the z-axis.
Weight symmetry is also a disclosure of Shenoha et al. U.S. Pat. No. 5,333,863 and this patent likewise follows the Hoglund patent at least in respect of the angulation of the club head shaft-receiving recess being at a substantial angle of inclination to the z-axis. Other examples of this type of club structure are shown in Solheim U.S. Pat. No. 3,042,405 and Paquette U.S. Pat. No. 5,308,069.
In somewhat similar pursuit to pendulum-type clubs, Reinberg U.S. Pat. No. 5,176,379 talks of imparting "neutral balance" to golf clubs by the use of weight offsetting outriggers secured to a club for balancing the same. Reinberg's club head shaft-receiving recess is, unlike the foregoing patented structures, in alignment with the z-axis. Limitation is seen, however, in this arrangement in that Reinberg requires symmetry in his club head fully in the x-axis and in the y-axis aside the recess. The same may be said of the structures disclosed in Dalton U.S. Pat. No. 4,138,117.
Another consideration of long-standing in the design of golf clubs is so-called "top spin" facility. Lawton U.S. Pat. No. 1,525,137 advised in 1925 of the value of imparting curvature to a putter ball engaging surface to impart "overspin" to the ball.
The following patents show various top spin surface arrangements: Barr U.S. Pat. No. 3,989,257; Thompson U.S. Pat. No. 4,162,074; Nebbia U.S. Pat. No. 4,902,015; Tucker U.S. Pat. No. 4,964,639; Garcia U.S. Pat. No. 5,303,923 and Sneed U.S. Pat. No. 5,382,019.
Limitation is seen in that all such top spin surfaces are constituted by the same material as the club head.
By way of further indication of prior art practices in the design of golf clubs, note is made of Clark et al. U.S. Pat. No. 4,253,667 and Tucker U.S. Pat. No. 4,964,639. Clark et al. advise of weighting practices, such as forming cavities in club heads and loading the cavities with shot held in place by a matrix. Tucker discloses application of a resilient member, such as a polyurethane rubber, to the front face of a putter to provide "feel" and protection.